U.S. patent application number 10/816173 was filed with the patent office on 2005-01-13 for cervical interspinous process distraction implant and method of implantation.
This patent application is currently assigned to St. Francis Medical Technologies, Inc.. Invention is credited to Flynn, John, Hsu, Ken Y., Markwart, Jay A., Mitchell, Steve, Winslow, Charles J., Yerby, Scott, Zucherman, James F..
Application Number | 20050010298 10/816173 |
Document ID | / |
Family ID | 34714338 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050010298 |
Kind Code |
A1 |
Zucherman, James F. ; et
al. |
January 13, 2005 |
Cervical interspinous process distraction implant and method of
implantation
Abstract
An implant for positioning between the spinous processes of
cervical vertebrae include first and second wings for lateral
positioning and a spacer located between the adjacent spinous
processes. The implant can be positioned using minimally invasive
procedures without modifying the bone or severing ligaments. The
implant is shaped in accordance with the anatomy of the spine.
Inventors: |
Zucherman, James F.; (San
Francisco, CA) ; Hsu, Ken Y.; (San Francisco, CA)
; Winslow, Charles J.; (Walnut Creek, CA) ; Flynn,
John; (Concord, CA) ; Mitchell, Steve;
(Pleasant Hill, CA) ; Yerby, Scott; (Montara,
CA) ; Markwart, Jay A.; (Castro Valley, CA) |
Correspondence
Address: |
FLIESLER MEYER, LLP
FOUR EMBARCADERO CENTER
SUITE 400
SAN FRANCISCO
CA
94111
US
|
Assignee: |
St. Francis Medical Technologies,
Inc.
Alameda
CA
|
Family ID: |
34714338 |
Appl. No.: |
10/816173 |
Filed: |
April 1, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60472817 |
May 22, 2003 |
|
|
|
Current U.S.
Class: |
623/17.16 ;
606/249; 606/279; 606/90; 623/17.11 |
Current CPC
Class: |
A61B 17/7068
20130101 |
Class at
Publication: |
623/017.16 ;
623/017.11; 606/061; 606/090 |
International
Class: |
A61F 002/44; A61B
017/70 |
Claims
What is claimed:
1. A device for relieving pain associated with the vertebrae of the
cervical spine and surrounding tissues and structures, by
maintaining and/or adding distraction between adjacent cervical
vertebrae when positioned between the spinous processes of adjacent
cervical vertebrae, without detracting from the rotation of the
cervical vertebrae relative to each other, the implant comprising:
1. a wedge-shaped spacer; 2. a wedge-shaped wing; and 3. a
wedge-shaped distraction guide.
2. The implant of claim 1 wherein the spacer has smooth, flat
surfaces and smooth, rounded edges to create a wedge for varying
distraction of adjacent cervical vertebrae.
3. The implant of claim 1 wherein the cross-sectional shape of the
wing has smooth, flat surfaces and smooth, rounded edges to create
a wedge for varying distraction of adjacent cervical vertebrae.
4. The implant of claim 1 wherein the wing is continuous with the
spacer.
5. The implant of claim 1 wherein the distraction guide is
continuous with the spacer.
6. The implant of claim 1 wherein the spacer is rotatable.
7. The implant of claim 1 including a second wing.
8. The implant of claim 1 wherein the spacer can rotate relative to
the wing and the distraction guide.
9. The implant of claim 1 wherein the first wing is provided at an
obtuse angle to the spacer
10. The implant of claim 1 wherein the first wing has a posterior
end and an anterior end, and the posterior end does not extend as
far beyond the posterior end of the spacer as the anterior end
extends anteriorly to the anterior end of the spacer.
11. A device for relieving pain associated with the vertebrae of
the cervical spine and surrounding tissues and structures, by
maintaining and/or adding distraction between adjacent cervical
vertebrae when positioned between the spinous processes of adjacent
cervical vertebrae, without detracting from the rotation of the
cervical vertebrae relative to each other, the implant comprising:
1. a wedge-shaped distraction guide; 2. a wedge-shaped spacer
associated with the wedge-shaped distraction guide, which spacer,
when urged between the spinous process of the adjacent cervical
vertebrae, allows flexion but not extension of the neck and creates
a contact surface with the bone of the spinous processes that
increases as the wedge-like spacer moves anteriorly, whereby the
implant distributes the distraction forces on the spinous processes
over the contact surface; and 3. a wedge-like wing extending from
and continuous with one end of the spacer to maintain lateral
placement of the spacer.
12. The implant of claim 11 wherein the spacer is rotatable.
13. The implant of claim 11 wherein the spacer is rotatable
relative to said wing.
14. The implant of claim 11 wherein the first wing is provided at
an obtuse angle to the spacer.
15. The implant of claim 11 wherein the spacer can rotate relative
to the wing and the distraction guide.
16. The implant of claim 11 wherein the first wing has a posterior
end and an anterior end, and the posterior end does not extend as
far beyond the posterior end of the spacer as the anterior end
extends anteriorly to the anterior end of the spacer.
17. The implant of claim 11 wherein the cross-sectional shape of
the spacer is selected from the group consisting of tear-drop,
wedge, ellipse, and oval.
18. An implant for relieving pain associated with adjacent cervical
vertebrae of the spine, that have a range of rotation relative to
each other in a scissor-like motion, which implant is positionable
between the spinous processes of adjacent cervical vertebrae, the
implant comprising: 1. a wedge-shaped spacer; 2. a wedge-shaped
first wing connected with the spacer; 3. a wedge-shaped distraction
guide, the distraction guide extending from the spacer at the end
distal to the first wing; and 4. a wedge-shaped second wing that
connects with the spacer.
19. The implant in claim 18 wherein the spacer has a
cross-sectional shape selected from the group consisting of
tear-drop, wedge, ellipse, and oval.
20. The implant of claim 18 wherein the first wing has a posterior
end and an anterior end, and the posterior end does not extend as
far beyond the posterior end of the spacer as the anterior end
extends anteriorly to the anterior end of the spacer.
21. The implant of claim 18 wherein the spacer is rotatable.
22. The implant of claim 18 wherein the second wing has a tongue
extending therefrom for use in securing the second wing to the
spacer.
23. The implant of claim 22 wherein portions of the tongue
extending from the second wing define a bore; wherein the spacer
has a bore compatible with the bore through the tongue; and a
fastener compatible with the bore of the spacer and the bore
through the tongue and that can secure the second wing to the
spacer.
24. The implant in claim 23 wherein the second wing has an anterior
side and a posterior side.
25. The implant in claim 18 wherein the posterior side of the first
wing and the posterior side of the second wing extend no further
than the posterior side of the spacer in a posterior direction.
26. The implant in claim 13 wherein the first wing and the second
wing have an anterior side and a posterior side, and the anterior
side of the first wing and of the second wing are angled outward
relative to each other to accommodate the anatomy of the adjacent
spinous processes of the cervical spine.
27. The implant of claim 18 wherein the spacer has an indentation
and the second wing includes an exterior that can made with the
indentation.
28. The implant of claim 18 wherein said second wing has an
indentation and the spacer has an extension that can mate with the
indentation of the second wing.
29. The implant of claim 18 wherein a hole of the second wing
allows the second wing to be received over the distraction guide to
connect with the spacer toward the end of the spacer adjacent to
the distraction guide.
30. The implant of claim 18 wherein the hinge has a protrusion at
an end of the hinge furthest from the lip.
31. The implant of claim 18 including a member for securing the
second wing to the spacer when the second wing is received over the
distraction guide onto the spacer and adjacent to the distraction
guide.
32. A device for relieving pain associated with the vertebrae of
the cervical spine and surrounding tissues and structures, by
maintaining and/or adding distraction between adjacent cervical
vertebrae when positioned between the spinous processes of adjacent
cervical vertebrae, without detracting from the rotation of the
cervical vertebrae relative to each other, the implant comprising:
1. a wedge-shaped spacer; 2. a bore in the spacer; 3. a
wedge-shaped first wing attached at one end of a longitudinal axis
of the spacer; 4. a wedge-shaped distraction guide at the end of
the longitudinal axis of the spacer distal to the first wing; 5. a
wedge-shaped second wing that is separate from the spacer,
distraction guide, and first wing, and is received over the
distraction guide and attached to the spacer during surgery after
the distraction guide, spacer, and first wing are positioned; 6. a
tongue extending from the second wing; 7. a bore through the tongue
of the second wing; and 8. a fastener to join and hold the second
wing to the spacer once the second wing is received over the
distraction guide and the bore of the tongue of the second wing and
the bore of the spacer are aligned.
33. The implant of claim 32 wherein the spacer is rotatably
connected with the first wing, the second wing, and the distraction
guide.
34. An implant for relieving pain associated with the vertebrae of
the cervical spine and surrounding tissues and structures, by
maintaining and/or adding distraction between adjacent cervical
vertebrae when positioned between the spinous processes of adjacent
cervical vertebrae, without detracting from rotation of the
cervical vertebrae relative to each other, the implant comprising:
1. a wedge-shaped spacer; 2. a wedge-shaped first wing extending
from one end of the longitudinal axis of the spacer; 3. a
wedge-shaped distraction guide extending from the end of the
longitudinal axis of the spacer distal to the first wing; 4. a
wedge-shaped second wing separate from the spacer, distraction
guide, and first wing that is attached to the spacer at the end of
the longitudinal axis of the spacer distal to the first wing during
surgery, after positioning the distraction guide, spacer and first
wing; and 5. a system to secure the second wing to the spacer.
35. An implant for relieving pain associated with the vertebrae of
the cervical spine and surrounding tissues and structures, by
maintaining and/or adding distraction between adjacent cervical
vertebrae when positioned between the spinous processes of adjacent
cervical vertebrae, without detracting from rotation of the
cervical vertebrae relative to each other, the implant comprising:
1. a wedge-shaped spacer with a longitudinal axis, which spacer
maintains and/or adds distraction when positioned between the
spinous processes of adjacent cervical vertebrae; 2. a wedge-shaped
distraction guide at one end of the longitudinal axis of the spacer
to introduce distraction between the spinous processes of adjacent
cervical vertebrae prior to insertion and positioning of the
spacer; 3. a wedge-shaped first wing at the end of the longitudinal
axis distal to the distraction guide to maintain lateral
positioning of the implant; and 4. a keep ring placed around the
spinous processes in the way of backward displacement of the
implant.
36. A method for implanting an implant between the spinous
processes of cervical vertebrae comprising the steps of : inserting
a first portion of the implant including a spacer and a distraction
end laterally; inserting a second portion of the implant including
a wing laterally from an opposite direction from the insertion of
the first portion; and fastening the second portion to the first
portion.
37. The method of claim 36 wherein the fastening step includes
interference-fitting the second portion onto the first portion.
38. The method of claim 36 wherein the fastening step includes
applying a fastener to the second and the first portion along a
posterior to anterior direction.
39. The method of claim 36 wherein the fastening step includes
causing a protrusion of one of the first portion and the second
portion to mate with an indentation of the other of the first
portion and the second portion.
40. The method of claim 36 including implanting the implant without
severing the ligamentum nuchae.
41. The method of claim 36 including implanting the implant without
altering the spinous processes.
42. A device that can relieve pain associated with the spine and
the tissues surrounding the spine comprising: a first wing; a
spacer; a distraction guide; wherein said spacer is elongated in
cross-section and said first wing is elongated in cross-section in
the same direction that said spacer is elongated; and said
distraction guide extends from said spacer.
43. The device of claim 42 wherein said first wing and said spacer
are wedge-shaped in cross-section.
44. The device of claim 42 wherein said first wing and said spacer
are wedge-shaped in cross-section with the wedge shape of the first
wing points in about the same direction as the wedge shape of the
spacer.
45. The device of claim 43 including a second wing that is
wedge-shaped.
46. The device of claim 42 including a second wing having an
aperture that is shaped to be received over the distraction
guide.
47. The device of claim 42 wherein said distraction guide extends
from the spacer and the second wing has an aperture that is shaped
to be received over the distraction guide and engaged with the
spacer.
48. The device of claim 42 wherein said first wing is elliptical in
shape and the spacer is wedge-shaped.
49. The device of claim 48 wherein said second wing is elliptical
in shape.
50. The device of claim 42 wherein said spacer is rotatable.
51. The device of claim 42 wherein said spacer is rotatably mounted
relative to the first wing and the distraction guide.
52. The device of claim 42 wherein said first wing has an anterior
end and a posterior end and the anterior end extends past the
spacer and the posterior end ends with the spacer.
53. The device of claim 42 wherein said first wing has an anterior
end and a posterior end and the anterior end extends past the
spacer and the posterior end does not extend past the spacer.
54. The device of claim 42 wherein said first wing has an anterior
end and a posterior end and the anterior end extends past the
spacer and the posterior end is truncated.
55. The device of clam 52 including a second wing and the second
wing has an anterior end and a posterior end and the anterior end
extends past the spacer and the posterior end ends with the
spacer.
56. The device of claim 53 including a second wing and the second
wing has an anterior end and a posterior end and the anterior end
extends past the spacer and the posterior end does not extend past
the spacer.
57. The device of claim 54 including a second wing and the second
wing has an anterior end and a posterior end and the anterior end
extends past the spacer and the posterior end is truncated.
58. The device of claim 42 including a second wing, and wherein
said first and second wings diverge from each other.
59. The device of claim 42 including a second wing, and wherein
said first and second wings are positioned at obtuse angles to the
spacer.
60. The device of claim 42 including a second wing and wherein said
first and second wings have anterior ends that are directed toward
an anterior of a patient and wherein said anterior ends diverge
from each other.
61. The device of claim 42 including a keep that is adapted for
being secured to a spinous process in order to block motion of the
spacer in a posterior direction.
62. The method of claim 36 including implanting the implant without
severing the suprsspinous ligament.
63. The device of claim 42 wherein the first wing is selected from
the group consisting of wedge-shaped, elliptical-shaped, tear drop
and ovoid-shaped.
64. The device of claim 42 including a second wing that can fit
over the distraction guide, which is selected from the group
consisting of wedge-shaped, elliptical-shaped, tear-drop shaped and
ovoid shaped.
65. The device of claim 42 wherein said spacer is selected from the
group consisting of any wedge-shaped, elliptical-shaped, tear drop
shaped and ovoid shaped.
Description
CLAIM OF PRIORITY
[0001] This application claims priority to U.S. Provisional
Application No. 60/472,817, filed May 22, 2003, entitletd "Cervical
Interspinous Process Distraction Implant and Method of
Implantation" (Attorney Docket No. KLYC-01087US0).
FIELD OF THE INVENTION
[0002] This invention relates to a cervical interspinous process
implant.
BACKGROUND OF THE INVENTION
[0003] The spinal column is a bio-mechanical structure composed
primarily of ligaments, muscles, vertebrae and intervertebral
disks. The bio-mechanical functions of the spine include: (1)
support of the body, which involves the transfer of the weight and
the bending movements of the head, trunk and arms to the pelvis and
legs, (2) complex physiological motion between these parts, and (3)
protection of the spinal cord and the nerve roots.
[0004] As the present society ages, it is anticipated that there
will be an increase in adverse spinal conditions which are
characteristic of older people. By way of example only, with aging
comes an increase in spinal stenosis (including, but not limited
to, central canal and lateral stenosis), and facet arthropathy.
Spinal stenosis results in a reduction foraminal area (i.e., the
available space for the passage of nerves and blood vessels) which
compresses the cervical nerve roots and causes radicular pain.
Humpreys, S. C. et al., Flexion and traction effect on
C5-C6foraminal space, Arch. Phys. Med. Rehabil., vol. 79 at 1105
(September 1998). Another symptom of spinal stenosis is myelopathy,
which results in neck pain and muscle weakness. Id. Extension and
ipsilateral rotation of the neck further reduces the foraminal area
and contributes to pain, nerve root compression and neural injury.
Id.; Yoo, J. U. et al., Effect ofcervical spine motion on the
neuroforaminal dimensions of human cervical spine, Spine, vol. 17
at 1131 (Nov. 10, 1992). In contrast, neck flexion increases the
foraminal area. Humpreys, S. C. et al., at 1105.
[0005] Pain associated with stenosis can be relieved by medication
and/or surgery. It is desirable to eliminate the need for major
surgery for all individuals, and in particular, for the
elderly.
[0006] Accordingly, a need exists to develop spine implants that
alleviate pain caused by spinal stenosis and other such conditions
caused by damage to, or degeneration of, the cervical spine. Such
implants would distract, or increase the space between, the
vertebrae to increase the foraminal area and reduce pressure on the
nerves and blood vessels of the cervical spine.
[0007] A further need exists for development of a minimally
invasive surgical implantation method for cervical spine implants
that preserves the physiology of the spine.
[0008] Further, a need exists for an implant that accommodates the
distinct anatomical structures of the spine, minimizes further
trauma to the spine, and obviates the need for invasive methods of
surgical implantation. Addifionally, a need exists to address
adverse spinal conditions that are exacerbated by spinal
extension.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1 and 2. FIG. 1 provides a perspective view of an
embodiment of an implant of the present invention having a spacer,
a distraction guide, and a wing with a cross-sectional elliptical
shape. The spacer has a teardrop shape in cross-section
perpendicular to its longitudinal axis. FIG. 2 is an end view of
the embodiment of the invention in FIG. 1.
[0010] FIGS. 3 and 4. FIG. 3 is a perspective view of another
embodiment of the invention having awing that is teardrop-shaped in
cross-section substantially perpendicular to the longitudinal axis
of the spacer. FIG. 4 is an end view of a second wing for the
embodiment of the invention of FIG. 3.
[0011] FIGS. 5, 6, and 7. FIG. 5 is a perspective view of an
embodiment of the invention having a rotatable spacer and a wing
that is elliptical in cross-section. FIG. 6 is a perspective view
of an embodiment of the invention having a rotatable spacer with
two wings that are teardrop-shaped in cross-section. The second
wing becomes connected with the spacer after the distraction guide,
spacer, and wing are positioned in the cervical spine during
surgery. FIG. 7 depicts the axis of rotation as seen from an end
view of the embodiment of the invention of FIG. 6.
[0012] FIGS. 8, 9A, and 9B. FIG. 8 is a perspective view of an
embodiment of the invention with a wing that is truncated at its
posterior end. FIG. 9A is an end view of an embodiment of the
invention with a wing truncated at its posterior end, with a
rotatable spacer. FIG. 9B is a truncated second wing for the
two-winged version of the embodiment of the invention of FIG.
9A.
[0013] FIGS. 10, 11 and 12. FIG. 10 is a plan view of an embodiment
of the invention where a screw is used to secure a second wing to
the spacer. FIG. 11 shows a perspective view of the second wing of
this embodiment of the invention. FIG. 12 shows a perspective view
of this embodiment of the invention.
[0014] FIGS. 13A, 13B, 14A and 14B. FIG. 13A is a side view of an
embodiment of a second wing of the invention, depicting a flexible
hinge mechanism for securing the second wing to the implant during
surgery. FIG. 13B is a side-sectional view of the second wing of
FIG. 13A through line 13B-13B. FIG. 14A is a plan view of the first
wing, spacer, and distraction guide depicting the indentation in
the spacer that fits with the hinge of the second wing of the
embodiment of FIGS. 13A and 13B. FIG. 14B is a front view of the
second wing with flexible hinge of the embodiment of FIGS. 13A and
13B.
[0015] FIGS. 15A, 15B, and 16. FIG. 15A is a top view of the an
embodiment of the invention of FIG. 3, positioned between the
spinous processes of adjacent cervical vertebrae, which embodiment
has wings with anterior ends directed away from the center of the
spacer, and truncated posterior ends. FIG. 15B is a top view of the
implant of FIG. 15A. FIG. 16 is a top view of two such implants of
the invention as seen in FIG. 15, positioned in the cervical
spine.
[0016] FIG. 17 is a side view of two implants of the invention
positioned in the cervical spine, with stops or keeps at the distal
ends of the spinous processes.
[0017] FIG. 18 depicts a method of the invention for surgically
implanting an embodiment of the implant of the invention adjacent
to cervical spinous processes of a patient.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0018] The embodiment of the invention includes a cervical spine
implant for alleviating discomfort associated with the cervical
spine without damage to the bones or other anatomical structures
associated with the spine. The embodiment also encompasses a method
for minimally invasive surgical implantation.
[0019] An embodiment of cervical spine implant of the invention
taught herein is adapted specifically to accommodate the anatomy of
the cervical spine and to distract the vertebrae to increase the
foraminal area and relieve pressure on the nerve roots. This
embodiment of the implant is shaped with smooth, broad sides so
that, when it is positioned during surgical implantation between
the spinous processes of adjacent cervical vertebrae, the implant
distributes the forces acting on it from the bones of the cervical
spine. Thus positioned, the implant distracts the cervical spine to
alleviate the pressure and restrictions on blood vessels and nerves
affected by stenosis and other spinal conditions.
[0020] The embodiment of the invention further discloses a method
for minimally invasive surgical implantation. The method for
implantation taught herein accommodates structures associated with
the cervical spine, and minimizes the need for invasive surgery. As
only one example, it is of obvious importance to avoid surgical
injury to the ligamentum nuchae (supraspinous ligament)in the
dorsal neck, a structure which cushions the spinous processes of
the upper cervical vertebrae.
[0021] While the cervical spine implant and method for relieving
pain address the needs of the elderly for reliefofsymptoms of
stenosis and the like, the embodiment of the invention also can be
used with individuals of all ages and sizes where distraction of
the spinous processes would be beneficial.
[0022] The implant is characterized in one embodiment as including
a distraction guide, a spacer, and a wing. The distraction guide
extends from one end of the spacer and is shaped so that it can
distract the spinous processes of adjacent cervical vertebrae so
that the spacer then can be urged into place between the spinous
processes. A single lateral retaining unit called a wing prevents
lateral displacement and rejection of the implant. The wing either
extends from or is attached to the spacer.
[0023] In another embodiment of the invention, the implant includes
a first unit having a spacer with a distraction guide and a first
wing. The embodiment further includes a second wing which fits over
the distraction guide to connect with the spacer, and a means for
securing the second wing to the spacer. The two wings prevent
lateral displacement and rejection of the implant.
[0024] In a further embodiment of the present invention, the
implant includes a spacer that is rotatable relative to the wing of
the implant. The spacer, which is tear-dropped shaped in
cross-section, is received over the shaft of the implant and can
rotate thereon about the shaft. It is to be understood that the
spacer need not be teardrop-shaped in cross-section; rather, other
forms are possible, including but not limited to cylindrical,
ovoid, elliptical, and the like.
[0025] It is to be understood that the cortical bone of the spinous
processes is stronger at an anterior position, near the vertebral
bodies of the vertebra, than at a posterior position distally
located from the vertebral bodies. The advantage to using a
rotatable spacer is that the rotation allows the surgeon more
easily to position the implant anteriorly between spinous processes
of adjacent cervical vertebrae.
[0026] An additional feature of the implant is its flat surfaces
for load bearing. The flat surfaces in contact with the bone
distribute the forces that bear on the bones and the implant
because of the distraction.
[0027] As maybe required for securing the lateral position of the
implant between the spinous processes, a second wing can be
connected with the spacer on the end of the spacer that joins with
the distraction guide. To connect the second wing, the second wing
passes over the distraction guide and is received by the spacer. A
fastener is used to secure the second wing to the spacer.
[0028] In yet another embodiment of the implant, the wing or wings
have truncated posterior ends to avoid or minimize interaction of
the implants and interference with neck rotation. For example, an
implant with extended posterior wings, positioned between cervical
vertebrae five and six, and a similar implant, placed between
cervical vertebrae six and seven, might interfere with each other
at the posterior ends of the wings during cervical rotation,
depending on the dimensions of a particular patient's vertebrae and
surrounding structures. Truncating the posterior ends of the wings
can avoid the undesirable consequences of two implants'
interaction.
[0029] In a further embodiment of the present invention, the
anterior portions of the first and second wings flare outward at an
angle from the spacer and away from the anterior ends of each
other, in order to accommodate the wedge shape of spinous processes
of the certain cervical vertebrae of the cervical spine.
[0030] In another embodiment, stops or keeps are placed around the
posterior ends of the spinous processes of adjacent cervical
vertebrae between which the implant of any of the above described
embodiments is positioned. The keeps prevent backward displacement
of the implant. The keeps can be made ofa biocompatible, flexible
polymer. Addifionally, the keeps can be made of stainless steel,
titanium, or a shape memory material such as Nitinol.
[0031] It is to be understood that the distraction guide, spacer,
and wings can be of various shapes. For example, the distraction
guide can be wedge-shaped or any other shape that introduces
distraction between spinous processes of adjacent cervical
vertebrae. The spacers, too, can have alternative shapes, defined
by their cross sections as teardrop, elliptical, ovoid, etc., which
would provide smooth edges and a flat and smooth contact surface
area between the spinous processes and the spacer to distribute the
forces placed thereon by the bone. The wings also might be
teardrop-shaped, elliptical, ovoid, etc., in cross-section, or any
other shape that provides smooth flat surfaces and rounded
edges.
[0032] In yet another aspect of the invention, a method is
presented for relieving pain due to the development of, by way of
example only, stenosis and facet arthropathy of the cervical spine.
The method is comprised of the steps of accessing the spinous
processes of adjacent cervical vertebrae and implanting a cervical
spinal distraction device in order to achieve the desired
distraction and to maintain that distraction.
[0033] One aspect of the method taught is the use of a guide wire
through the neck to guide the positioning of the implant while
monitoring the implantation via x-ray.
[0034] Other aspects, objects, features and elements of embodiments
of the invention are described or evident from the accompanying
specification, claims and figures.
[0035] The following description is presented to enable any person
skilled in the art to make and use the invention. Various
modifications to the embodiments described will be readily apparent
to those skilled in the art, and the principles defined herein can
be applied to other embodiments and applications without departing
from the spirit and scope of the present invention as defined by
the appended claims. Thus, the present invention is not intended to
be limited to the embodiments shown, but is to be accorded the
widest scope consistent with the principles and features disclosed
herein. To the extent necessary to achieve a complete understanding
of the invention disclosed, the specification and drawings of all
patents and patent applications cited in this application are
incorporated herein by reference.
[0036] An embodiment of an implant 100 of the invention is depicted
in FIGS. 1 and 2. This implant 100 includes a wing 130, a spacer
120, and a lead-in tissue expander, or a distraction guide 110. The
distraction guide 110 in this particular embodiment is
wedge-shaped, i.e., has an expanding cross-section from the end
distal 140 to the region 150 where the guide 110 joins with the
spacer 120. As such, the distraction guide functions to initiate
distraction of the soft tissue and the spinous processes when the
implant 100 is surgically inserted between the spinous processes.
It is to be understood that the distraction guide can be pointed
and the like, in order to facilitate insertion of the implant
between the spinous processes of adjacent cervical vertebrae. It is
advantageous that the insertion technique disturb as little of the
bone and surrounding tissue or ligaments as possible in order to
(1) reduce trauma to the site and promote early healing; and (2)
prevent destabilization of the normal anatomy. It is to be noted
that with the present embodiment, and all of the embodiments
herein, there is no requirement to remove any of the bone of the
spinous processes and no requirement to remove or sever ligaments
and tissues immediately associated with the spinous processes.
Specifically, it is unnecessary to remove or sever the ligamentum
nuchae, (supraspinous ligament) which partially cushions the
spinous processes of the upper cervical vertebrae.
[0037] Additionally, as depicted in FIGS. 1 and 2, the wing 130 in
this embodiment 100 is elliptically-shaped in a cross-section
perpendicular to the longitudinal axis 125 of the spacer and
distraction guide. As illustrated in the embodiment of FIG. 3, and
as discussed in more detail herein, the wing 130 can have
alternative shapes in cross-section, such as teardrop, wedge,
circular, oval, ovoid, football-shaped, and rectangular-shaped with
rounded corners and other shapes, and be within the spirit and
scope of the invention. The wing 130 has an anterior portion 133
and a posterior portion 135.
[0038] Further, as also can be seen in FIGS. 1, 2, and 3 and other
embodiments to be discussed herein, the spacer 120 is
teardrop-shaped in cross-section perpendicular to the spacer's
longitudinal axis 125. The spacer 120, like the wing 130, can have
alternative shapes such as circular, wedge, oval, ovoid,
football-shaped, and rectangular-shaped with rounded corners and
other shapes, and be within the spirit and scope of the invention.
The shape of the spacer selected for a particular patient should
accommodate the wedge-like space between adjacent cervical spinous
processes and thus allow the surgeon to position the implant as
close as possible anteriorly, near the vertebral bodies.
[0039] It should be appreciated that the shape selected for the
spacer 120 should create a smooth, flat and relatively broad
contact area between the implant 100 and the spinous processes of
the vertebrae that are to be subject to distraction. Increasing the
contact surface area between the implant and the spinous processes
distributes the force and load between the spinous frame and the
implant. Generally, a teardrop or wedge-shaped spacer allows for
more load-bearing contact between the spacer and the spinous
process.
[0040] It is to be understood also that the implant 100 can have
two wings, with a second wing 160 (FIG. 4) separate from the
distraction guide 110, spacer 120 and first wing 130. The second
wing can be connected to the end of the spacer 120 distal from the
first wing 130. It should be noted that the second wing 160, like
the first wing 130, can prevent lateral displacement of the implant
100relative to an individual patient's cervical spine anatomy. In
FIG. 4, the second wing 160 is teardrop-shaped and wedge-shaped in
cross-section. The wider section or end 162 of the teardrop shape
is the posterior end of the second wing 160 and the narrower
section or end 169 is the anterior end of the second wing 160.
Unlike the first wing 130, however, the sides of the second wing 60
define a space 170 with a lip 180 that allows the second wing 160
to pass over ditraction guide 110 to meet and connect with the
spacer 120. The second wing 160 is then secured to the spacer 120
toward the end of the spacer located distally from the first wing
140. The second wing 60 is implanted once the distraction guide
110, spacer 120, and first wing 130 are inserted as a unit between
the spinous processes of adjacent cervical vertebrae.
[0041] It is to be understood that the implant is preferably made
in two pieces. The first piece includes the first wing 130, the
spacer 120, and the distraction guide 110. The second piece
includes the second wing 160. Each piece can be made in a number of
ways known in the art including by machining and molding. Each
piece, as will be more fully discussed can be made of any material
that is bio-compatible with the body of a patient. For example the
implants can be made of stainless steel and titanium. Additionally,
a shape memory metal such as Nitinol, which is a combination of
titanium and nickel, can also be used. Further polymers such as
described later can also be used. It is further to be understood
that the implant can be formed with multiple pieces and with the
pieces appropriately joined together. Further the implant can be
formed as one piece or joined together as one piece and be within
the spirit and scope of the invention, but without some of the
advantages of the embodiment of the invention as exist with a two
piece embodiment as shown in FIGS. 1, 2, 3, and 4.
[0042] A further embodiment 200 of the invention is depicted in
FIGS. 5 and 6. In this embodiment 200, the spacer 210 is rotatable
about its longitudinal axis 240, FIG. 7 relative to a first wing
130 (FIG. 5), or relative to two wings with respect to an
alternative embodiment of the invention (FIG. 6). The spacer may
also be rotatable or fixed, relative to the distraction guide 110.
The spacer 210 has a bore 220 running the length of its
longitudinal axis 240, with holes at both ends of the spacer 210,
and a shaft 230inserted through the bore 220 and connecting with
the distraction guide 110 and first wing 130. As discussed above,
it maybe advantageous to position any of the implants taught herein
as close as possible to the vertebral bodies. The rotatable spacer
210 can accommodate the bone structures of the cervical spine as
the implant is inserted between the spinous processes as it follows
the distraction guide laterally into position. Spacer rotation
accommodates the anatomy of the spinous processes relative to the
wings of the implant. Thus, the rotatable spacer 210 improves the
positioning of the spacer independent of the wings relative to the
spinous processes. The embodiment of FIG. 6 has a first wing 130
and if desired, a second wing 160 similar to the wing depicted in
the embodiment of FIG. 3. As will be discussed below, the shape of
the wings in FIGS. 3 and 6 is such that the implants accommodate
the twisting of the cervical spine along its axis as, for example,
the head of a patient turning from side to side.
[0043] FIGS. 8, 9A, and 9B show a perspective view (FIG. 8) and an
end view (FIG. 9A) of another embodiment 300 of the invention,
wherein the posterior portion 135 of the teardrop-shaped first wing
130 is truncated at end 310, making the first wing 130 more ovoid.
In this configuration, the anterior portion 133 of the first wing
130 is longer than the truncated posterior end 310 of the first
wing 130. The embodiment 300 can also have a rotatable spacer 210.
It should be appreciated, as illustrated in FIG. 9B, that the
second wing in a two-winged version of this embodiment of the
invention 300, would be a truncated second wing 350 with a
truncated posterior end 340.
[0044] The purpose of embodiment 300, as with the other
embodiments, is to minimize the possibility of interference of
implants positioned between the spinous processes of adjacent pairs
of cervical vertebrae, e.g., implants between cervical vertebrae
five and six, and between six and seven. During rotation of the
neck, the spinous process move past each other in a scissor-like
motion. Each cervical vertebra can rotate relative to the next
adjacent cervical vertebra in the general range of about 6.degree.
-12.degree.. It is to be understood that in addition, about 50
percent of the rotational movement of the neck is accomplished by
the top two neck vertebrae. Thus, such embodiments can accommodate
neck rotation without adjacent embodiments interfering with each
other.
[0045] With respect to the prior embodiments which have first and
second wings, the second wing 160, FIG. 4 can be designed to be
interference-fit onto the spacer 120 or, in the case of a rotatable
spacer 210, FIG. 5, a portion of the end of the distraction guide
110 adjacent to the spacer 120. The spacer 120 is associated with
the first wing 130. Thus, there is no additional attachment device
to fasten the second wing 160 relative to the remainder of the
implant. However, as described below and as desired, various
fasteners can be used to secure the second wing 160 relative to the
remainder of the implant.
[0046] FIGS. 10, 11, and 12 depict an embodiment 400 with a
teardrop-shaped second wing 410 that has a bore 420 through a
tongue 430 at the posterior end of the second wing 160. The bore on
the second wing 420 is brought into alignment with a corresponding
bore 440 on the spacer 120 when the second wing 160 is brought into
position by surgical insertion relative to the rest of the implant.
A threaded screw 450 is inserted through the aligned bores in a
posterior-anterior direction to secure the second wing 160 to the
spacer 120. The direction of insertion from a posterior to an
anterior direction has the screw engaging the bores and the rest of
the implant along a direction that is generally perpendicular to
the longitudinal axis of the spacer 125 (FIGS. 1 and 3). This
orientation is most convenient when the surgeon is required to use
screw 450 to secure the second wing 160 to the rest of the implant.
Other securing mechanisms using a member inserted into
corresponding bores 420, 440 on the spacer 120 and second wing 160
are within the spirit of the invention. It should be understood
that a rotatable spacer 210 also can be accommodated by this
embodiment. With a rotatable spacer 210, the second wing 160 would
be attached to the end of the distraction guide 110 that is located
adjacent to 115 the rotatable spacer 210.
[0047] FIGS. 13A, 13B, 14A, and 14B depict a further embodiment 500
wherein the second wing 160 is secured to the spacer 120 by a
mechanism including a flexible hinge 515, with a protrusion 530 on
the end of the hinge 510 adjacent to the lip 180 of the hole 170
defined by portions of the second wing 160. The securing mechanism
also encompasses an indentation 540 on the spacer 120, wherein the
indentation accommodates the protrusion 530 on the end of the
flexible hinge 515. During surgery, after insertion of the
distraction guide 110, spacer 120, and first wing 130, the second
wing 160 is received over the distraction guide 110 and the spacer
120. As the second wing 160 is received by the spacer 120, the
flexible hinge 515 and its protrusion 530 deflect until the
protrusion 530 meets adjoins with the indentation 540 in the spacer
120, securing the second wing 160 to the spacer 120. Again in
embodiments where the spacer can rotate, the indentation 540 is
located on an end of the distraction guide 110 that is adjacent to
150 the rotatable spacer 210. With respect to the flexible hinge
515, this hinge is in a preferred embodiment formed with the second
wing 160 and designed in such a way that it can flex as the hinge
515 is urged over the distraction guide 110 and the spacer 120 and
then allow the protrusion 530 to be deposited into the indentation
540. Alternatively, it can be appreciated that the indentation 540
can exist in the second wing 160 and the flexible hinge 515 and the
protrusion 530 can exist on the spacer 120 in order to mate the
second wing 160 to the spacer 120. Still alternatively, the
flexible hinge 515 can be replaced with a flexible protrusion that
can be flexed into engagement with the indentation 540 in the
embodiment with the indentation 540 in the spacer 120 or in the
embodiment with the indentation 540 in the second wing 160.
[0048] FIGS. 15A, 15B, and 16. These figures illustrate an
embodiment 600 wherein the first wing 130 and second wing 160 flare
out at an angle away from the spacer 120 and away from each other.
That is the anterior ends of the first and second wings flare away
from each other. The cervical spinous processes are themselves
wedge-shaped when seen from a top view. Accordingly, it is
advantageous that the implant 600 accommodate this wedge shape so
that the implant 600 can be positioned as close as possible to the
vertebral bodies of the spine where the load of the spine is
carried. Thus the first 130 and the second wings 160 are positioned
relative to the spacer, whether the spacer is fixed 120 or
rotatable 210, so that the wings flare out as the wings approach
the vertebral body of the spine. FIG. 15B depicts a top view of the
implant 600 of FIG. 15A. As is evident from FIG. 15B, the first
wing 130 is formed at an angle with respect to a line that is
perpendicular to the spacer 120. In a preferred embodiment, the
angle is about 30.degree., with a preferable range .theta. from
about 15.degree. to about 45.degree.. Other angles of the first
wing 130 relative to the spacer 120 are contemplated and in
accordance with the invention. The second wing 160 is also
preferably provided at an angle of about 30.degree. relative to a
line that is perpendicular to the spacer with a preferable range
.theta. from about 15.degree. to about 45.degree.. In other words,
the wings form an obtuse angle with respect to the spacer 120 in
this embodiment. The second wing 160 defines an inner hole 170
which is outlined by the lip 180. As is evident, the lip 180 is
provided at an angle relative to the rest of the second wing 160 so
that when the lip 180 is urged into contact with the spacer 120,
the second wing 160 has the desired angle relative to the spacer
120. As discussed above, there are various ways that the second
wing 160 is secured to the spacer 120. FIG. 15A depicts a top view
of one such implant 600 placed between the spinous processes of
adjacent cervical vertebrae. FIG. 16 is a top view illustrating two
layers of distracting implants 600 with flared wings.
[0049] FIG. 17 illustrates another embodiment 700 that uses "stops"
or "keeps" 710, which are rings of flexible biocompatible material,
positioned around the spinous processes of adjacent cervical
vertebrae and located posteriorly to the implant. The keeps 710
prevent backward displacement of the implants. The keeps generally
include a ring 710 which has a slit 720 that goes completely
through the ring. The keeps 710 can be somewhat sprung apart, so
that the keep 710 can be fit over the end of the spinous process
and then allowed to spring back together in order to hold a
position on the spinous process. The keep 710 can act as a block to
the spacer 120 in order to prevent the implant from movement in a
posterior direction.
[0050] It is to be understood that the implant and/or portions
thereof can be fabricated from somewhat flexible and/or deflectable
material. In these embodiments, the implant and/or portions thereof
is made out of a polymer, more specifically, the polymer is a
thermoplastic. Still more specifically, the polymer is a polyketone
known as polyetheretherketone (PEEK). Still more specifically, the
material is PEEK450G, which is an unfilled PEEK approved for
medical implantation available from Victrex of Lancashire, Great
Britain. The Victrex website is located at www.matweb.com, or see
Boedeker, at www.boedeker.com. Other sources of this material
include Gharda located in Panoli, India, at www.ghardapolymers.com.
The implant and/or portions thereof can be formed by extrusion,
injection, compression molding and/or machining techniques. The
material specified has appropriate physical and mechanical
properties and is suitable for carrying and spreading the physical
load between the spinous process. Further in-this embodiment, the
PEEK has the following additional approximate properties:
1 Property Value Density 1.3 g/cc Rockwell M 99 Rockwell R 126
Tensile Strength 97 MPa Modulus of Elasticity 3.5 GPa Flexural
Modulus 4.1 GPa
[0051] In an another preferred embodiment, the implant is comprised
at least, in part of titanium or stainless steel, or other suitable
implant material which may be radiopaque and, in part, of a
radiolucent material that does not show up under x-ray or other
type of imaging. In a preferred embodiment, the first wing 130 and
second wing 160 and the shaft 230 are comprised of such a
radiopaque material such as titanium and the spacer 120 and the
distraction guide 110 are comprised of a radiolucent material such
as, for example, PEEK or other radiolucent materials described
herein. In an embodiment which includes the first wing 130, with
the spacer 120 and the distraction guide 110, under imaging, the
implant looks like a "T". In an embodiment which includes both a
first and a second wing, the spacer and the tissue expander, under
imaging, the implant looks like an "H". This embodiment allows the
doctor to have a clearer view of the spine under imaging without
the implant interfering as much with the view of the bone
structure. Alternatively, the entire implant can be comprised of
titanium or stainless steel.
[0052] It should be noted that the material selected may also be
filled. For example, other grades of PEEK are also available and
contemplated, such as 30% glass-filled or 30% carbon-filled,
provided such materials are cleared for use in implantable devices
bythe FDA, or other regulatory body. Glass-filled PEEK reduces the
expansion rate and increases the flexural modulus of PEEK relative
to that which is unfilled. The resulting product is known to be
ideal for improved strength, stiffness, or stability. Carbon-filled
PEEK is known to enhance the compressive strength and stiffness of
PEEK and lower its expansion rate. Carbon-filled PEEK offers wear
resistance and load carrying capability.
[0053] In this embodiment, as described above, the implant is
manufactured from PEEK, available from Victrex. As will be
appreciated, other suitable similarly biocompatible thermoplastic
or thermoplastic polycondensate materials that resist fatigue, have
good memory, are flexible, and/or deflectable, have very low
moisture absorption, and good wear and/or abrasion resistance, can
be used without departing from the scope of the invention. The
spacer can also be comprised of polyetherketoneketone (PEKK).
[0054] Other material that can be used include polyetherketone
(PEK), polyetherketoneetherketoneketone (PEKEKK), and
polyetheretherketoneketone (PEEKK), and generally a
polyaryletheretherketone. Further, other polyketones can be used as
well as other thermoplastics.
[0055] Reference to appropriate polymers that can be used in the
implant can be made to the following documents, all of which are
incorporated herein by reference. These documents include: PCT
Publication WO 02/02158 A1, dated Jan. 10, 2002, entitled
"Bio-Compatible Polymeric Materials;" PCT Publication WO 02/00275
A1, dated Jan. 3, 2002, entitled "Bio-Compatible Polymeric
Materials;" and, PCT Publication WO 02/00270 A1, dated Jan. 3,
2002, entitled "Bio-Compatible Polymeric Materials."
[0056] Other materials such as Bionate.RTM., polycarbonate
urethane, available from the Polymer Technology Group, Berkeley,
Calif., may also be appropriate because of the good oxidative
stability, biocompatibility, mechanical strength and abrasion
resistance. Other thermoplastic materials and other high molecular
weight polymers can be used.
[0057] A minimally invasive surgical method for implanting the
cervical distraction device in the cervical spine is disclosed and
taught herein. In this method, FIG. 18, preferably a guide wire 880
is inserted through a placement network 890 into the neck of the
implant recipient. The guide wire 880 is used to locate where the
implant is to be placed relative to the cervical spine, including
the spinous processes. Once the guide wire 880 is positioned with
the aid of imaging techniques, an incision is made on the side of
the neck about so that the first unit of the embodiment of the
invention, which includes the distraction guide 110, the spacer
120, and the first wing 130 can be positioned in the neck thorough
an incision and along a line that is about perpendicular to the
guide wire 880 and directed at the end of the guide wire. The first
unit is so inserted into the neck of the patient. Preferably during
insertion, the distraction end pokes through or separates the
tissue without severing the tissue. Next, the second wing 160 is
inserted along a line that is generally colinear with the line over
which the first unit is inserted but from the opposite side of the
neck. The anatomy of the neck is such that it is most convenient
and minimally invasive to enter the neck from the side with respect
to the first unit and the second wing 160. The second wing 160 is
mated to the first unit and, in this particular embodiment, the
second wing 160 is snapped into engagement with the first unit. In
an alternative embodiment, the second wing 160 is attached to-the
first unit by the use of a fastener, and in particular by a screw
450. The screw 450 is positioned using a screw driving mechanism
that is directed along a posterior to anterior line somewhat
parallel to the guide wire 880. This posterior to anterior line
aids the physician in viewing and securing the second wing 160 to
the first unit.
[0058] It is to be understood that the various features of the
various embodiments can be combined with other embodiments of the
invention and be within the spirit and scope of the invention.
Thus, for example only, the embodiment of FIG. 1 can have truncated
wings as depicted in other embodiments.
Industrial Applicability
[0059] The above establishes that the present invention can be used
to relieve pain associated with the cervical spine. The present
invention is minimally invasive and can be used on an outpatient
basis.
[0060] Additional aspects, objects and advantages of the invention
can be obtained through a review of the appended claims and
figures.
[0061] It is to be understood that other embodiments can be
fabricated and come within the spirit and scope of the claims.
[0062] The foregoing description of preferred embodiments of the
present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Many
modifications and variations will be apparent to one of the
ordinary skill in the relevant arts. The embodiments were chosen
and described in order to best explain the principles of the
invention and its partial application, thereby enabling others
skilled in the art to understand the invention for various
embodiments and with various modifications that are suited to the
particular use contemplated. It is intended that the scopes of the
invention are defined by the claims and their equivalence.
* * * * *
References